MODELING CHAR OXIDATION AS A FUNCTION OF PRESSURE ...

Introduction
Appendix A: Experiments
The properties of char are dependent on preparation conditions, such as
temperature, heating rate, and oxygen and steam concentrations. In particular, questions
have arisen in the literature regarding the comparison of high temperature char oxidation
rates obtained in flat-flame burner experiments versus rates obtained in drop tube and
other reactors. The purpose of this experimental work is to explore how steam and
oxygen concentrations affect the properties of char, such as N 2 surface area, CO 2 surface
area, apparent density, true density, and most important of all, TGA reactivity and high
temperature reactivity. The work in this appendix was performed in a one-year contract
(No. DE-AC21-93MC30040) with U.S. Department of Energy (DOE) and the Advanced
Fuel Research (AFR). This work appears in the appendix to preserve the modeling focus
in the main text of this dissertation.
Chars were prepared in a flat-flame reactor under four different conditions,
varying post-flame steam and oxygen concentrations. To determine the effects of ambient
steam concentration on the char properties, chars were produced in the post-flame
products of: 1) a flame using CH 4 as the principal fuel, and 2) a flame using CO as the
principal fuel. The post-flame steam concentration was reduced substantially when CO
was used as the principal fuel. To determine the effects of ambient oxygen concentration
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